Homeless adolescents and young adults are considered one of the most vulnerable populations worldwide with an estimated 100 million globally (UNESCO, 2007), and 500,000 to 2.8 million in the U.S. alone (Bucher, 2008; Cooper, 2006). A multitude of studies document high rates of alcohol and drug use, sexual risk behaviors and physical and mental health vulnerabilities (Robertson & Toro, 1999). Homeless adolescents and young adults frequently report histories of childhood physical and/or sexual abuse (Robertson & Toro, 1999) and are disconnected from family, housing and social services (Gaetz, 2004). The purpose of this study was to identify the most effective intervention for addressing substance use, as well as secondary outcomes including housing, mental health problems, and victimization among three theoretically distinct but empirically-supported interventions: the Community Reinforcement Approach (CRA, Meyers & Smith, 1995), Motivational Enhancement Therapy (MET, Miller & Rollnick, 2013) and case management (CM).

Substance use disorders are common among homeless adolescents and young adults, with studies estimating that 69 to 86 percent meet diagnostic criteria for at least one substance use disorder (Baer, Ginzler, & Peterson, 2003; Kipke, Montogemery, Simon, & Iverson, 1997). In addition to the direct negative effects of substance use, there are significant social, legal and physical health consequences (Edidin, Ganim, Hunter, & Karnik, 2012). For example, substance use is associated with other mental health disorders (Johnson, Whitbeck, & Hoyt, 2005) and increases adolescent’s and young adult’s risk of victimization on the streets (Greene, Ennett, & Ringwalt, 1997; Whitbeck, Hoyt, & Yoder, 1999). Substance use can inhibit one’s exit from homelessness and increases the potential for chronic homelessness into adulthood (Greene et al., 1997; Robertson & Toro, 1999). Overall, treatment for substance use disorders is a priority when intervening with homeless adolescents and young adults, not only because of the high prevalence of substance use disorders in this population, but also because of the multitude of negative consequences associated with it.

Furthermore, the problems experienced by homeless youth are interrelated, and the treatment of substance use problems has been associated with improvements in other affected domains including depressive symptoms, internalizing and externalizing problems, coping and victimization experiences (Slesnick et al., 2007; Williams & Chang, 2000). Despite the challenges experienced by these youth, current research offers limited guidance regarding how to intervene and treat this population (Eddin et al., 2012; Robertson & Toro, 1999). Homeless youth present with challenges not faced by those who are not experiencing homelessness. In particular, they are less connected to familial, institutional or other supports, and rarely enter substance use treatment on a voluntary basis, though they can be engaged in treatment through outreach (Fisk, Rakfeldt, & McCormack, 2006). Because of the range of difficulties, providing substance use treatment for people who are homeless cannot be separated from the larger needs for assistance with housing, employment and income (Kertesz et al., 2007; Milby et al., 2000). For example, recovery outcomes can be enhanced, and social isolation diminished, through the use of advocates who assertively link persons who are homeless to community-based support programs (National Alliance to End Homelessness, 2006).

Recent reviews of the adolescent substance use treatment literature identify several effective individual, group, and family interventions (Tanner-Smith et al., 2013; Waldron & Turner, 2008). Some evidence suggests that family therapy interventions outperform other interventions, but more research supporting this conclusion is needed (Tanner-Smith et al., 2013). Given the range of available effective treatment options, researchers suggest that cost effectiveness (Tanner-Smith et al., 2013) and response to treatment (Waldron & Turner, 2008) should be considered when selecting a treatment. However, as noted, very few intervention studies have been conducted with homeless youth, and those few studies targeted a wide range of outcomes using various interventions. In two recent literature reviews, Altena and colleagues (2010) identified 11intervention studies while Slesnick and colleagues (2009) identified 14 studies. These few studies tested individual, family, group, and street-based interventions focused on substance use, mental health, sexual and HIV risk, and employment.

Identifying effective interventions is also complicated by the fact that subgroups of runaway and homeless adolescents and young adults exist, with different intervention needs among them (Chamberlain & MacKenzie, 2004; Haber & Toro, 2004). That is, presence on the streets is considered a marker of problem severity. Shelter-recruited adolescents tend to be younger, and often have never spent a night on the streets (Robertson & Toro, 1999). Family reunification is the primary goal of runaway shelters, with family therapy a recommended approach (Slesnick, Dashora, Letcher, Erdem, & Serovich, 2009; Teare, Peterson, Furst, & Authier, 1994). In contrast, street-living homeless adolescents and young adults rarely access institutional settings (shelters, foster care) or family for assistance because these systems are no longer perceived to meet their needs (Marshall & Bhugra, 1996). Community-based interventions offered in low-demand settings such as drop-in centers are recommended for street-living adolescents and young adults (Chamberlain & MacKenzie, 2004). Drop-in centers offer youth a bridge from the streets to the mainstream, with few requirements placed upon youth (Slesnick et al., 2008). These centers usually address basic needs and seek to connect youth to more intensive services as trust develops. Promising interventions for street-living adolescents and young adults include case management, brief motivational interviewing, and behavioral interventions (Altena, Brilleslijper-Kater, & Wolf, 2010; Slesnick et al., 2009). Information on the relative performance of these promising interventions can offer evidence supporting intervention options for those seeking to serve this population.